Natural killer T (NKT)-B-cell interactions promote prolonged antibody responses and long-term memory to pneumococcal capsular polysaccharides

Antibodies directed against microbial polysaccharides are a critical component of protective immune responses and vaccines. We used nanoparticles coexpressing pneumococcal capsular polysaccharides and a cell wall lipid antigen analog to model NKT-B-cell interactions. Our study demonstrated CD1d-restricted cognate interactions, isotype switch, affinity maturation, and long-term memory, despite the apparent failure of NKT cells to differentiate into follicular helper cells. The findings demonstrate the importance of nonconventional sources of help for B cells responding to polysaccharide antigens.